Crowd and riot control have always been a problem for law enforcement officials, not only on a national scale but on an international scale as well. Typically, crowds and rioters have been dispersed by tear gas, water cannons, physical force and the like. The result is that law enforcement officials, even though dressed in riot gear or protective clothing, have been unable to disperse large unruly crowds, without being injured or injuring the participants.
Normally, this type of civil disorder takes place in open street areas, with the participants scattered throughout the region and tending to travel as a crowd through and along adjacent streets. The size of the group may increase as further participants join them from the surrounding streets. The ability to see and to hear what is going on in the riot area tends to be a factor in the spread and inability to exercise effective control.
In the case of prison riots, for example, rioting inmates may take control of a segment of the institution, frequently with hostages. History has proven that prison riots generally result in fatalities or serious bodily damage to the prison population or the law enforcement officials on the scene.
As is apparent, it would be desirable to provide a system which is easily transportable, easy to use, essentially harmless to people, but which functions to disorient people as they tend to travel through a barrier.
It is known in the prior art to use foams in fighting fires. Typically such foams are formed from water-soluble surfactants of the perfluorocarbon type which may be dispensed from a variety of different types of equipment, all well known in the art. One such typical material is known in the art as AFFF, see U.S. Pat. Nos. 3,258,423; 3,562,156 and 3,772,195, for example. Generically these materials are also known as FCS and HCS materials, e.g., fluorocarbon surfactants and hydrocarbon surfactants. Variations include those AFFF compositions which include a fluorochemical synergist known as F-amide and an FCS called F-AMPS, see for example U.S. Pat. Nos. 4,090,967 and 4,014,926. These foam producing materials are known to produce high-expansion foams which are known to spread over the surface in order to suppress vaporization of gasoline, which is the principal reason these materials were developed. Other patents which disclose similar materials are U.S. Pat. No. 4,090,967, United Kingdom Pat. Nos. 1,230,980 of 1971 and 1,126,027 of 1968, and Canadian Pat. No. 842,252, for example.
Foams from the above and other equivalent materials tend to be of small envelope or bubble size and flowable, the latter being one of the desirable qualities for use in fighting fires. Moreover, the foams may be formed relatively easily at the site of application by any number of different devices, all well known in the art. Portable units of various sizes as well as truck mounted units are commercially available for forming and dispensing various amounts of foamed material. For example, units are available which dispense from 2,000 to 15,000 or more cubic feet of foam per minute. Dispensing units include water reaction motors, electrically powered units, turbine units, compressed gas driven units and the like. Some of the dispensing equipment includes a tubular member which may be from two feet to ten feet in diameter, connected to the foam generator, and used to control the direction of foam discharge. The foam is discharged from the open end of the tubular member remote from the foam generator. The result is that an enormous amount of foam may be quickly dispensed from a relatively small unit in a relatively short time using a relatively small amount of water and foaming agent. Since the foam includes a surfactant, it tends to flow easily and spread quickly over the contact surfaces which it readily wets. Such foams may also be dispensed from high velocity nozzles and projected a relatively long distance and with sufficient accuracy to reach a designated target area.
Typically, the foams above described are sometimes referred to as expanded foams, having an expansion ratio of 50 to 1 to 1000 to 1. These types of foams do not have sufficient strength to remain in a three-dimensional shape, for example a mound, for any significant length of time. Where the foam is dispensed from a tubular member, customarily referred to as a chute, the chute may be of a length of one hundred feet or more, with the foam being dispensed from the open end of the chute remote from the generator. Generators are known which have an output or discharge opening which may vary from one square foot to as much as twenty-five or more square feet.
The foams described, dispensed by known equipment and techniques, tend to have a relatively long life since collapse of the foam is due principally to evaporation of the water component of the foam. Thus, in the absence of heat or flame, the foam tends to remain fairly stable for a relatively long period. However, it is also true that the foam tends to spread laterally rather quickly since this is one of the desirable features in its use as a fire-fighting material.
It is believed to be known in the prior art that fire fighting foam generating equipment may be installed on site to foam an area for the purposes of fighting fires. Even though known, there appears to have been little practical use of foams as a riot or crowd control medium apparently because of the inability to deliver the foam to the desired location and to maintain the foam in the immediate region needed for crowd and riot control. In other words, there does not exist in the prior art a methodology for containing the foam in the desired location, nor was it apparently recognized that the key to the successful use of foams as a riot control medium was dependent upon confining the foam so as to form an interdiction barrier. As near as can be determined, little use has been made in open areas, such as streets, large rooms and the like, of foams as a riot control system because it may not have been recognized that the effectiveness of the foam for that purpose could be significantly increased by confining the foam.